Steel making slags are the byproducts of the steel making processes. Typically, steel making slags are produced from the basic oxygen furnace of the steel mills, and there are several kinds of slags produced from iron and steel making facilities. Blast furnaces are generally utilized to reduce iron oxide to iron. The slag generated from blast furnaces is referred to as BF slag. Next, the iron may go through a desulfurization step to remove sulfur from the iron. The slag generated here may be called desulfurization slag, and it may be rich in sulfur. Lastly, the desulfurized iron is placed in a basic oxygen furnace (BOF) to convert iron to steel by removing carbon and other impurities. Slags may also be produced from electric arc furnaces (EAF).
It currently is believed that the steel industry in the United States generates about 30 million tons of byproducts each year. The majority of these byproducts are present in various forms of slags, sludges and dusts. There may be about 12.5 million tons of BF slag, 6 million tons of BOF type slag, 4.5 million tons of EAF slag, 1.5 million tons of desulfurization slag, 2 million tons of BF and BOF sludges and 1 million tons of dust. Previous efforts of processing such byproducts have achieved only limited success. As a result, large amounts of byproducts of various types and qualities have been stockpiled at steel mills where available space is diminishing. Additionally, valuable minerals and materials lie within the slag, going unused and essentially wasted.